US Bridges

Risdon Road over Sdm Channel

Fair

Contra Costa County, California · 0.25 MI SW Oak Grove · Structure no. 28C0276

Built
1970
55 years old
Condition
Fair
inspected November 2023
Type
Culvert
Concrete Continuous
Length
31 ft
2 main spans
Daily traffic
450
2000 count
Owner
City
City or Municipal Highway Agency

About this bridge

Risdon Road over Sdm Channel is a concrete continuous culvert carrying Risdon Road over Sdm Channel in Contra Costa County, California. It was built in 1970, so it is 55 years old, older than the California average of 54.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 6 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

It carries about 450 vehicles a day, roughly 2% of them trucks, projected to reach 578 by 2041. The structure is 31 ft (9.4 m) long and 58 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesRisdon Road
CrossesSdm Channel
Location0.25 MI SW Oak Grove
RouteCity Street 0
CountyContra Costa County
StateCalifornia
Coordinates37.94311, -122.03349
Functional classUrban Local

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Channel and channel protection9 ExcellentNo problems noted.
Culvert6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44.6 US tons
Inventory rating26.8 US tons

Structure

Structure typeCulvert
MaterialConcrete Continuous
DeckNot applicable
Main spans2
Design loadUnknown
Structure length31 ft (9.4 m)
Longest span15 ft (4.5 m)
Deck width58 ft (17.7 m)
Roadway width34 ft (10.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic450 (2000)
Projected traffic578 by 2041
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Risdon Road over Sdm Channel built?

It was built in 1970, making it 55 years old in 2025.

What condition is Risdon Road over Sdm Channel in?

The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in November 2023.

How much traffic does Risdon Road over Sdm Channel carry?

About 450 vehicles per day (2000 count), of which roughly 2% are trucks.

How long is Risdon Road over Sdm Channel?

The structure is 31 ft (9.4 m) long with a longest span of 15 ft (4.5 m) and a deck 58 ft wide.

Who owns Risdon Road over Sdm Channel?

It is owned by the City or Municipal Highway Agency.